I believe щ is pronounced like the sh-sound in "shoes" and ш is pronounced like the sh-sound in "shrimp" or "shop". Be aware of how you place your tongue when pronouncing the words, in "shoes" (щ) your tongue is closer to your teeth and in "shrimp" (ш) your tongue glides further back in your mouth. I hope this helps!
Because of the logic of the language. Like some other languages as Turkish
TTS stands for Text-to-Speech. This is what a voice synthesizer is technically called.
Nowadays very few "voice synthesizers" on the market actually synthesize voice. The most common way to make a commercial Text-to-Speech engine is to record dozens of hours of a voice talent's spech and then extract many pieces of of voice from there. Effectively, you use a large database of phonemes and allophones, which (in theory) covers all possible sounds found in the words of the language read in any environment with any intonation.
- in reality some combinations of sounds are fairly rare. The texts recorded for building a TTS are carefully designed to cover even the rarest sounds. Still, a language naturally uses some sounds way more often that others, so you need thousands of sentences to get a good coverage of less common sounds in different environments.
Another way is to use HMM (hidden markov models) to "teach" the engine how to synthesize sounds using hours and hours of recording as a role model. It usually ends up being more monotone and robotic (though, less prone to "broken tape recorder" effect), so few synths for sale use it. The free engine RH Voice uses such method.
Because it hasn't been taught yet?
Plus, Wiktionary at https://en.wiktionary.org/wiki/%D1%8F%D0%B2%D0%BB%D1%8F%D1%82%D1%8C%D1%81%D1%8F#Russian indicates that this is a third meaning, so somewhat low on the list of likely meanings.
Plus, it takes instrumental, which I don't think has been taught yet, either.
It is perhaps more likely to be related to Ancient Greek "γυνή", which is at the root of English words such as "gynaecology".
For more details, including the word's various pronunciations, take a look at: https://en.wiktionary.org/wiki/%CE%B3%CF%85%CE%BD%CE%AE